The Emerging Infections Network (EIN) is a forum for infectious diseases consultants and public health officials to report information on clinical phenomena and epidemiological issues with public health significance. Any diagnostic or therapeutic recommendations and all opinions presented are those of the individual contributor. They do not necessarily represent the views of EIN, IDSA (EIN’s sponsor), or the Centers for Disease Control and Prevention (CDC), which funds EIN. The reader assumes all risks in using this information.
EIN members recently reported several cases of Mycobacterium abscessus, highlighting the range of infections this organism causes as well as the difficulty in treating it.
A member in California shared the case of a 17-year-old girl with cystic fibrosis and recent decline in lung function, who over the past year had three bronchoalveolar lavage (BAL) cultures that grew M. abscessus only. “Due to her declining function and only M. abscessus growing, we feel that she should receive treatment, which is where we’ve faced a hurdle,” the member wrote, given the patient’s drug reactions and resistance profile.
A respondent in Florida described a patient with persistent M. abscessus bacteraemia, who had been bacteremic for approximately eight weeks. “Thus far, he is on tigecycline/cefoxitin/imipenem and oral clarithromycin, the member wrote. The patient also has an inferior vena cava (IVC) filter and an implantable cardioverter defibrillator (ICD)/pacer, which several EIN respondents suggested may be the source of the infection.
A Pennsylvania EIN member described a 33-year-old man who cut his hand while swimming in an indoor pool and developed persistent cellulitis, which responded to intermittent courses of trimethoprim and sulfamethoxazole (TMP-SMX). A biopsy showed a ruptured epidermoid cyst and acute and chronic granulomatous inflammation, with no bone, joint, or tendon involvement.
Cultures grew M. abscessus/chelonae, and the patient was started on clarithromycin, doxycycline, and a combination of TMP-SMX, with “minimal improvement after three weeks,” the member wrote. “I have tentatively put him on a combination of clarithromycin and tigecycline. Any suggestions? Would anyone add clofazimine?”
Clofazimine does have in vitro activity, but there are no studies that demonstrate the effectiveness of clofazimine in the treatment of M. abscessus. Dosing and treatment duration are not currently defined. Clofazimine is not marketed in the U.S., but physicians can gain access to the drug for patients with nontuberculous mycobacterial (NTM) disease through the Food and Drug Administration. Application forms, a description of the application process, and an explanation for the medication’s limited distribution are available online.
Treating these infections is further complicated by the recent finding that M. abscessus actually consists of three distinct species (M. abscessus sensu stricto, M. massilinese, and M. bolleti), an EIN member in California noted. These frequently carry an erm gene, which is often inducible, meaning that “standard susceptibility testing often fails to detect macrolide/azalide resistance in the absence of a preincubation step or prolonged incubation (approximately 14 days),” the member continued.
This may account for the frequent failure of eradication of M. abscessus complex organisms in patients receiving clarithromycin or azithromycin as part of a two- or three-drug regimen. The EIN member shared several references:
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The Emerging Infections Network (EIN) is a provider-based sentinel network designed to help the public health community detect trends in emerging infectious diseases.
A joint project of IDSA and the Pediatric Infectious Diseases Society (PIDS) with funding from the Centers for Disease Control and Prevention (CDC), EIN tracks emerging infectious diseases and keeps the public health community up to date with new disease trends, difficult cases, and other issues affecting members’ clinical practices. The Network provides a great opportunity for members to share knowledge quickly across large geographical distances. Both IDSA and PIDS members are eligible to join. Click here for more information or to join EIN.
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